package com.gitee.kooder.examples;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.facet.DrillDownQuery;
import org.apache.lucene.facet.FacetResult;
import org.apache.lucene.facet.Facets;
import org.apache.lucene.facet.FacetsCollector;
import org.apache.lucene.facet.FacetsConfig;
import org.apache.lucene.facet.sortedset.DefaultSortedSetDocValuesReaderState;
import org.apache.lucene.facet.sortedset.SortedSetDocValuesFacetCounts;
import org.apache.lucene.facet.sortedset.SortedSetDocValuesFacetField;
import org.apache.lucene.facet.sortedset.SortedSetDocValuesReaderState;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.store.ByteBuffersDirectory;
import org.apache.lucene.store.Directory;

/** Shows simple usage of faceted indexing and search,
 *  using {@link SortedSetDocValuesFacetField} and {@link
 *  SortedSetDocValuesFacetCounts}.  */

public class SimpleSortedSetFacetsExample {

    private final Directory indexDir = new ByteBuffersDirectory();
    private final FacetsConfig config = new FacetsConfig();

    /** Empty constructor */
    public SimpleSortedSetFacetsExample() {
    }

    /** Build the example index. */
    private void index() throws IOException {
        IndexWriter indexWriter = new IndexWriter(indexDir, new IndexWriterConfig(
                new WhitespaceAnalyzer()).setOpenMode(OpenMode.CREATE));
        Document doc = new Document();
        doc.add(new SortedSetDocValuesFacetField("Author", "Bob"));
        doc.add(new SortedSetDocValuesFacetField("Publish Year", "2010"));
        indexWriter.addDocument(config.build(doc));

        doc = new Document();
        doc.add(new SortedSetDocValuesFacetField("Author", "Lisa"));
        doc.add(new SortedSetDocValuesFacetField("Publish Year", "2010"));
        indexWriter.addDocument(config.build(doc));

        doc = new Document();
        doc.add(new SortedSetDocValuesFacetField("Author", "Lisa"));
        doc.add(new SortedSetDocValuesFacetField("Publish Year", "2012"));
        indexWriter.addDocument(config.build(doc));

        doc = new Document();
        doc.add(new SortedSetDocValuesFacetField("Author", "Susan"));
        doc.add(new SortedSetDocValuesFacetField("Publish Year", "2012"));
        indexWriter.addDocument(config.build(doc));

        doc = new Document();
        doc.add(new SortedSetDocValuesFacetField("Author", "Frank"));
        doc.add(new SortedSetDocValuesFacetField("Publish Year", "1999"));
        indexWriter.addDocument(config.build(doc));

        indexWriter.close();
    }

    /** User runs a query and counts facets. */
    private List<FacetResult> search() throws IOException {
        DirectoryReader indexReader = DirectoryReader.open(indexDir);
        IndexSearcher searcher = new IndexSearcher(indexReader);
        SortedSetDocValuesReaderState state = new DefaultSortedSetDocValuesReaderState(indexReader);

        // Aggregatses the facet counts
        FacetsCollector fc = new FacetsCollector();

        // MatchAllDocsQuery is for "browsing" (counts facets
        // for all non-deleted docs in the index); normally
        // you'd use a "normal" query:
        FacetsCollector.search(searcher, new MatchAllDocsQuery(), 10, fc);

        // Retrieve results
        Facets facets = new SortedSetDocValuesFacetCounts(state, fc);

        List<FacetResult> results = new ArrayList<>();
        results.add(facets.getTopChildren(10, "Author"));
        results.add(facets.getTopChildren(10, "Publish Year"));
        indexReader.close();

        return results;
    }

    /** User drills down on 'Publish Year/2010'. */
    private FacetResult drillDown() throws IOException {
        DirectoryReader indexReader = DirectoryReader.open(indexDir);
        IndexSearcher searcher = new IndexSearcher(indexReader);
        SortedSetDocValuesReaderState state = new DefaultSortedSetDocValuesReaderState(indexReader);

        // Now user drills down on Publish Year/2010:
        DrillDownQuery q = new DrillDownQuery(config);
        q.add("Publish Year", "2010");
        FacetsCollector fc = new FacetsCollector();
        FacetsCollector.search(searcher, q, 10, fc);

        // Retrieve results
        Facets facets = new SortedSetDocValuesFacetCounts(state, fc);
        FacetResult result = facets.getTopChildren(10, "Author");
        indexReader.close();

        return result;
    }

    /** Runs the search example. */
    public List<FacetResult> runSearch() throws IOException {
        index();
        return search();
    }

    /** Runs the drill-down example. */
    public FacetResult runDrillDown() throws IOException {
        index();
        return drillDown();
    }

    /** Runs the search and drill-down examples and prints the results. */
    public static void main(String[] args) throws Exception {
        System.out.println("Facet counting example:");
        System.out.println("-----------------------");
        SimpleSortedSetFacetsExample example = new SimpleSortedSetFacetsExample();
        List<FacetResult> results = example.runSearch();
        System.out.println("Author: " + results.get(0));
        System.out.println("Publish Year: " + results.get(0));

        System.out.println("\n");
        System.out.println("Facet drill-down example (Publish Year/2010):");
        System.out.println("---------------------------------------------");
        System.out.println("Author: " + example.runDrillDown());
    }
}